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論文タイプ||論説, (法学部号 = Law and Politics)

Physical training has been shown to improve insulin action in simple obese and obese diabetic patients. On the other hand,the hyperketonemic effect of prolonged exercise in insulin-dependent diabetic patients is well recognized phenomenon. Recently, we have demonstrated that 60-min high-frequency (60Hz) stimulation produces a significant reduction in 3-hydroxybutyrate (3-OHBA) uptake in muscle not only in diabetic but also in control rats and that a reduction in 3-OHBA utilization in diabetics is found for 90 min after muscle constriction. In the present study. we measured extracellular 3-OHBA concentrations in 12Hz-stimulated muscle for five diabetic and five control rats by use of the microdialysis technique. The following results were obtained: 1. In control rats, there was no significant difference in 3-OHBA levels between before, during and after stimulation. 2. In diabetics, the dialysate 3-OHBA concentrations showed a significant increase during constriction and for 90 min after constriction. It is well known that 12Hz-stimuli is more aerobic in muscle than 60-Hz-stimuli. Therefore, it may be advisable that diabetic patients performe an aerobic exercise, in order to increase insulin action in peripheral tissue, after nearly normalization for metabolism by diet and insulin therapy, and so on.

Physical training has been shown to improve insulin action in simple obese and diabetic patients. On the other hand, the hyperketonemic effect of prolonged exercise in insulin-dependent diabetic patients is a well recognized phenomenon. Therefore, in order to evaluate the mechanism, especially the effect of exercise in ketone body metabolism m muscle, we measured extracellular acetoacetate (AcAc) concentrations in muscle of five diabetic and five control rats. The following results were obtained; 1. In control rats, constriction produced a significant rise in dialysate AcAc concentration which rapidly returned to pre-constriction levels after constriction. 2. In diabetics, the dialysate AcAc concentrations showed a significant increase during constriction and for 60 min after constriction. These results suggest that exercise results in a significant reduction in ketone body utilization in muscle not only in diabetic but also control rats and a reduction in ketone body utilization after muscle constriction in poorly-controlled diabetics plays a role in post-exercise hyperketonemia.

In order to elucidate the effects of skeletal muscle contraction and insulin on glucose uptake in exercised muscle, we studied 19 male Wistar rats by using microdialysis technique in both femoral muscles and jugular vein. Under the continuous somatostatin infusion (0.5 μg/kg·min) and bolus infusion of anti-insulin serum (0.3ml), which induced a complete suppresson of insulin secretion (plasma insulin levels were less than 3μU/ml), these rats were divided into 2 groups. One was that both femoral muscles were stimulated electrically (S). The other was that both thighs were kept resting without stimulation (C). The lactate concentration in dialysate were determined every 15minutes and the dialysate lactate concentration in muscle was a measure of glucose uptake. After somatostatin infusion (2 hours), insulin was infused continuously(6.0mU/kg·min) in both groups. The following results were obtained: 1. In S group., the dialysate lactate concentrations in muscle were significantly higher than that in jugular vein under the condition of complete suppression of insulin secretion. 2. In C group, the dialysate lactate levels in muscle were significantly lower than that in jugular vein under the above condition. 3. During inslin infusion, the increase in dialysate lactate concentration in muscle of S group was almost similar to that of C group. From these results, it could be confirmed that exercised muscle results in a large increase in glucose uptake even if insulin secretion is suppressed completely, and that insulin acts as an additive effect in exercised muscle.